Sphygmomanometer



Nov. 22, 1955 E. F. LARSON SPHYGMOMANOMETER 2 Sheets-Sheet 1 Filed July '7, 1954 5 i. We 1 m m A e f Nov. 22, 1955 E. F. LARSON SPHYGMOMANOMETER 2 Sheets-Sheet 2 Filed July 7. 1954 Mm m5 E? W A [Z06 F MJ E 3 Lw a EH5, m z 5 Z Z 7H 2 M 6 mm a UM N.

0 2 m1 w 6 M 5 V 6 0\ 3 4 Si United States Patent Oliice 2,724,381 Patented Nov. 22, 1955 2,724,331 SPHYGMOMANOMETER Elmer F. Larson, Arcadia, Calif. Application July 7, 1954, Serial No. 441,881

7 Claims. (21. rzs aas induced pulses of the circulating blood to overcome a built-upair pressure. in the device of the mentioned patent, a tank is filled with compressed air which is conducted past a telltale or sight to fill and constrict a band or cult around a limb to produce pressure on an artery.

By gradually increasing the air pressure in the tank to a critical point, the pressure of the blood incirculation is overcome to a stage that each pulsation of blood trying to overcome the air pressure in the cuii pumps a smaller volume of air out o f the cuff into a tube in which the sight is fully slidable. This volume of air propelsthe sight upwardly to an elevation that is relative to the blood pressure.

An object of the present invention is to provide improved means for critically controlling the air pressure and apprising the user that such critical pressure has been attained.

Another object of the invention is to provide means, as indicated, that apprises of reduction of air pressure below a desired minimum.

A further object of the invention is to provide means to vent the present apparatus to atmosphere.

A still further object of the invention is to provide novel means etfecting ready assembly of the components ofthe apparatus. i

The invention also has for its objects to provide. such means that are positive in operation, convenientin use, easily installed in a working position and easily disconnected therefrom, economical of manufacture; relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawings merely show and the following description merely describes, one embodiment of the present invention, which is given by way of illustration or example only;

In the drawings, like reference characters designate similar parts in the several views.

Fig. 1 is a side elevational view, partly in section, showing an instrument or device constructed in accordance with the present invention and shown in operative connection with an arm.

Fig. 2 is an enlarged front elevational view of the lower portion of Fig. 1.

Fig. 3 is a further enlarged cross-sectional view as taken on line 3-3 of Fig. 2.

Fig. 4 is a broken longitudinal sectional view as taken on line 4-4 of Fig. 1 and drawn to the scale of Fig. 2.

Fig. 5 is a cross-sectional view as taken on line 5-5 of Fig. 4.

Fig. 6 is a sectional view, to the scale of Fig. 3, as taken on line 6-6 of Fig. 4.

Fig. 7 is a front View of a component of the device in a position different from the position of said component as shown in Fig. 2.

The device that is illustrated comprises, generally, an air tank 10, an air inlet device 11 carried by said tank and connected to a compressible bulb 12 as by a flexible tube 13, an air outlet device 14 also carried by said tank, a sight tube 15 extending from device 14 and having a sight element 16 therein, adevice 17 at the lower end of tube 15 for passing air flowing past the sight to a cuff 18 through a flexible tube 19 and constituting telltale means to apprise of the pressure in the device, and means 20 for quickly and easily fastening the components of the device.

The air tank 10 is here shown as an enclosure in which the front wall 21 is provided with an opening 22 communicating with inlet device 11 and a similar opening 23 communicating with outlet device 14. As shown, said openings are preferably provided in the upper portion of wall 21 and in side-by-side arrangement.

The air inlet device 11 is shown as comprising a body 24 having a passage 25 in register with opening 22. A fitting 26 extends through opening 22 from the interior of the tank and is provided with a check valve 27that controls inlet of air from passage 25 to said tank interior. The tube 13 extends into communication with passage 25 which, as seen in Fig. 4, has a lateralextension 28 that opens at the side'of body 24.

Since fitting 26 passes through tank wall 21, the same constitutes means that locates body 24 on said wall.

The inlet device 11 further includes a safety limit valve '29 which is here shown as a rubber membrane 30 in superimposed position over the side of body 24 in which passage extension 28 opens. In practice, body 11 is formed of vulcanized rubber. Consequently, said membrane 30 may be vulcanized to the body and allowing the portion overstanding passage extension 28 to be free to be outwardly displaced or deflected by air pumped into passages 22 and 28 by bulb .12. The degree of deflection of said membrane is controlled by a flat spring 31 and can be controlled by an adjusting screw 32 which varies the deflection-limiting function of said flat spring.

The air outlet device 14 comprises a body 33 that is mounted on tank wall 21 and is provided with a passage 34 that is in direct communication with opening 23 in said wall. A preferably laterally extending regulatable air-venting member 35 is carried by said body 33. Said member 35 is shown as a tube 36 that is fitted to passage 34 and is aflixed to body 33 as by a pin 37. The interior of tube 36 is provided with compressible packing 38 which is adapted to be compressed or loosened, as desired, by a tapered compressing screw 39 carried by tube 36. Accordingly, air flow through vent holes 40 in said tube may be regulated by tightening or slacking off of screw 39. In this manner, the present device is provided with a regulatable air escape means that controls the time of the pressure test.

The sight tube 15 extends downward from passage 34 and, as is usual, is transparent. The sight element 16 may be either loosely fitted in said tube to allow slow bleeding of air therepast, or the same may have channels or other passages for the same purpose. The sight is otherwise solid but light in weight.

The device 17 is shown as comprising a body 41 having a passage 42 into which the lower end of sight tube 15 is fitted. Said passage 42 is in communication with a venting member 43 that is substantially similar to member 35 of device 14. Said passage also is connected to flexible tube 19 and it will be clear that air in tube 15, that moves past sight 16, enters tube 19 to cause inflation of cuif 18 and that member 43 constitutes a regulator for said air. 1 The device 17, as above indicated, also includes telltale means 44 that apprises the operator of the air pressure in the device. Said telltale means is controlled by air in an extension passage 45, a rubber membrane 46 cemented to the body side in which said extension 45 opens, a metallic escutcheon plate 47 clamping membrane 46 to the body and provided with an opening 48 opposite to extension 45, and a telltale 49 responsive to outward deflection of membrane of the portion framed by plate 47.

The telltale 49 is shown, in this instance, as a flag 50 that is divided into a red panel 51 and a black panel 52, an arm 53 mounting said flag and pivotally mounted in bearings 54 formed in plate 47, an eccentric or crank 55 formed in said arm and in engagement with membrane 46, and a light spring member 56 engaged with said crank to bias the flag to one position while deflection of membrane 46 moves the flag to another position. Said two positions are shown, respectively, in Figs. 2 and 7. In this manner, the panels 51 and 52 of flag 50 are moved with relation to a window 57 in a cover member 58 held in clamping engagement with devices 11, 14 and 17.

The device 17 further includes an air-bleeding valve 59 that is provided with an operating button 60 accessible from the front and extending through a boss 61 formed in cover member 58. Said valve may be an ordinary tire valve and is normally closed, as shown in Fig. 6. By pushing on button 60, said valve may be opened-to vent passage 42 and, therefore, the tank 10. a The means 20 is shown as a stud 62 extending through tank wall 21, and each body 33 and 41, each stud having a large head 63 preferably soldered to wall 21, and a cap screw or the like 64 passing through suitable holes in cover 58 and threadedly engaged with studs 62.

Although the same is not a feature of the present invention, the device here disclosed is provided with suitable scales 65 that may be read in connection with sight element 16. Said scales 65 are advantageously carried by cover 58 which is provided with skirt portions 66 which enclose the above-described components of the device.

The operation is as follows: v

The bulb 12 .is used to pump air into tank past ball check 27. A desired pressure in the tank is achieved by setting the screw 32 to allow the membrane 30 to be forced away from port 28 by excessive pressure. In practice, the tank is brought to a pressure of 120 mm. Since this pressure bleeds past the sight 16 (which is in its low position), the same is manifested on membrane 46 which is outwardly bulged into the opening 48 and, by moving crank 55 outwardly, moves flag 50 down to the position of Fig. 7. The red panel 51 is now opposite opening 57 in cover 58 and the same indicates that a pressure test is ready to be performed.

Since this 120 mm. pressure is imposed in culf 18, the reactive pressures brought about by pulsations of arterial blood effect elevation of the sight 16 in tube in accordance with the pressure of the blood as hereinbefore indicated. These pulsations cause the sight to move up and down or bounce.

As the test progresses, the venting members 35 and 43 slowly, and as regulated, bleed the pressure in the tank and when said pressure is lowered to say 60 mm., the test is considered to be finished. This becomes known to the operator because the flag 50 will move up to show its black panel 52 through window 57. I Somewhere in the range between 120 and 60 mm. is the critical pressure that is equal to the blood pressure. At this critical point, the sight will be elevated to maximum by a blood pulsation.

The venting means 35 and 43 also have the function of allowing blood pressure-pumped air to escape, thereby providing a control that limits or increases the rise of the sight 16. This function eliminates the need for vertical adjustment of the scales 65.

Said scales may be provided in any'desired manner to be read in connection with arm or leg arterial pressure and according to the different age groups.

While the foregoing has illustrated and described what is now contemplated to be the best mode of carrying out the invention, the construction is, of course, subject to modification without departing from the spirit and scope of the invention. It is, therefore, not desired to restrict the invention to the particular form of construction illustrated and described, but to cover all modifications that may fall within the scope of the appended claims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

l. A sphygmomanometer comprising a tank to store air under pressure, means to supply pressure air to said tank, a check valve controlling air flow into the tank, a pressure-limiting valve in said supply means and in advance of the check valve, an air outlet from said tank and terminating in a device to constrict around an artery, at sight element in said outlet moving in response to a pulsation of said artery when the air pressure in the outlet is substantially the same as the blood pressure in said artery, and adjustable means to gradually vent said outlet to reduce the air pressure from a point above to a point below that of the blood pressure.

2. A sphygmomanometer according to claim 1: a visual telltale controlled by the air pressure in the outlet and movable by said pressure to one position and returnable to another position upon reduction of the pressure below i a predetermined magnitude.

3. A sphygmomanometer according to claim 1: a visual telltale controlled by the air pressure in the outlet and movable by said pressure to one position and returnable to another position upon reduction of the pressure below a predetermined magnitude, said telltale comprising a pressure-distendable membrane, an arm movable by said membrane when distended, a flag on the free end of the arm and readable in connection with a window, and spring means biasing said arm in a direction to move the flag to one position relative to said window, said distended membrane moving the flag to another position relative to the window.

4. A sphygmomanometer according to claim 1: a normally-closed venting valve in said outlet, and push button means to open said valve to vent the outlet and the tank.

5. A sphygmomanometer comprising a tank to store air under pressure, means to supply pressure air to said tank, a check valve controlling air flow into the tank, a pressure-limiting valve in said supply means and in advance of the check valve, an air outlet from said tank and terminating in a device to constrict around an artery, a sight element in said outlet moving in response to a pulsation of said artery when the air pressure in the outlet is substantially the same as the blood pressure in said artery, an adjustable vent for said outlet between the sight element and the tank to gradually vent said outlet to reduce pressure in the tank from a point above .to a point below that of the blood pressure.

6. A sphygmomanometer according to claim 5: a second adjustable vent for said outlet and located between the sight element and the termination at the artery constricting device.

7. A sphygmomanometer according to claim 5: a second adjustable vent for said outlet and located between the sight element and the termination at the artery constricting device, and a manually-operable and normallyclosed valve in said outlet to vent the same to atmosphere.

References Cited in the file of this patent UNITED STATES PATENTS 2,076,642 Hubbard et al. Apr. 13, 1937 2,633,121 Larson Mar. 31, 1953 FOREIGN PATENTS 753,617 France Aug. 12, 1933 

